The IEEE 802.16 family of standards specifies Media Access Control (MAC) and Physical (PHY) layer protocols for WiMAX broadband wireless communications. Key entities in a WiMAX access network include Base Stations (BS), Relay Stations (RS), and Mobile Stations (MS). BS and MS are referred to as infrastructure stations while MS is regarded as a subscriber station.
To enhance the reliability of WiMAX, the 802.16 Working Group started a new Task Group, called IEEE 802.16n, which specifies operation of so called High-Reliability BS (HR-BS), High-Reliability RS (HR-RS), and High Reliability MS (HR-MS). A WiMAX network operating based on what to be specified in IEEE 802.16n will be referred to as HR-Network.
Among all requirements to enhance WiMAX reliability, HR-MS forwarding is specified.
HR-Network shall support HR-MS forwarding of user data and control signaling between HR-MS and HR-BS and between HR-MS and HR-RS. The control signaling and data transmission for the HR-MS to HR-MS direct link shall at least be capable of operating within the frequency band that the HR-BS operates. An association establishment shall be supported.